This radar display unit is typical of the sort of instrument used on ships in the 1970s to monitor the surrounding sea. It was made by Kelvin Hughes, one of the leading navigational instrument suppliers. It has a 12-inch metal-backed fluoride screen, on top of which is a plastic bearing cursor that has a degree scale marked on its outer edge and a bearing line across its diameter. The unit can be set to ranges up to 64 miles (103 km).